Definition and Basic Principle
- The hot runner system is a connecting system between the injection molding machine and the mold cavity,embedded in the mold.It allows the plastic melt to remain in a molten state for at least one cycle or more,preventing the melt from solidifying in the runner,which is commonly referred to as"runnerless molding."
Key Considerations
- Thermocouple Placement:Thermocouples should be placed in areas where the maximum temperature can be measured,i.e.,the region closest to the heat source. Internal Pressure Load:The allowable internal pressure load as a function of temperature is particularly important for hot runner nozzles,but relevant data is difficult to obtain.
- Gate Cross-Section Design:If the surface of the molded product only allows for a very small gate mark,the gate cross-section should be designed to be smaller,but this will increase.
Summary
Hot runner technology offers significant advantages in injection molding, such as shortened cycle times, cost reduction, and improved molding quality. However, it also has some limitations, including high mold costs, complex operation and maintenance, and high thermal equilibrium requirements. In practical applications, it is necessary to comprehensively consider these factors to fully leverage the advantages of hot runner technology while minimizing the impact of its limitations.